Package org.rrd4j.core

Class RrdRandomAccessFileBackend

java.lang.Object

org.rrd4j.core.RrdBackend

org.rrd4j.core.RrdRandomAccessFileBackend

All Implemented Interfaces:

RrdFileBackend

Direct Known Subclasses:

RrdSafeFileBackend

public class RrdRandomAccessFileBackend
extends RrdBackend
implements RrdFileBackend

Backend which is used to store RRD data to ordinary files on the disk. This was the default factory before 1.4.0 version. This backend is based on the RandomAccessFile class (java.io.* package).

Field Summary

Fields

Modifier and Type	Field	Description
protected RandomAccessFile	rafile	Random access file handle.

Fields inherited from class org.rrd4j.core.RrdBackend

BYTEORDER

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	RrdRandomAccessFileBackend(String path, boolean readOnly)	Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Method Summary

Modifier and Type	Method	Description
protected void	close()	Closes the underlying RRD file.
String	getCanonicalPath()	Returns canonical path to the file on the disk.
long	getLength()	Returns the number of RRD bytes in the underlying storage.
void	read(long offset, byte[] b)	Reads a number of bytes from the RRD file on the disk
protected void	setLength(long length)	Sets the number of bytes in the underlying RRD storage.
protected void	write(long offset, byte[] b)	Writes bytes to the underlying RRD file on the disk

Methods inherited from class org.rrd4j.core.RrdBackend

done, getCharBuffer, getFactory, getPath, getUri, isCachingAllowed, isInstanceCreated, readAll, readDouble, readDouble, readInt, readLong, readShort, readString, rrdClose, writeDouble, writeDouble, writeDouble, writeInt, writeLong, writeShort, writeString, writeString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

rafile

protected final RandomAccessFile rafile

Random access file handle.

Constructor Detail

RrdRandomAccessFileBackend

protected RrdRandomAccessFileBackend(String path,
                                     boolean readOnly)
                              throws IOException

Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.

Parameters:

path - Path to a file

readOnly - True, if file should be open in a read-only mode. False otherwise

Throws:

IOException - Thrown in case of I/O error

Method Detail

close

protected void close()
              throws IOException

Closes the underlying RRD file.

Specified by:

close in class RrdBackend

Throws:

IOException - Thrown in case of I/O error

write

protected void write(long offset,
                     byte[] b)
              throws IOException

Writes bytes to the underlying RRD file on the disk

Specified by:

write in class RrdBackend

Parameters:

offset - Starting file offset

b - Bytes to be written.

Throws:

IOException - Thrown in case of I/O error

read

public void read(long offset,
                 byte[] b)
          throws IOException

Reads a number of bytes from the RRD file on the disk

Specified by:

read in class RrdBackend

Parameters:

offset - Starting file offset

b - Buffer which receives bytes read from the file.

Throws:

IOException - Thrown in case of I/O error.

getCanonicalPath

public String getCanonicalPath()
                        throws IOException

Description copied from interface: RrdFileBackend

Returns canonical path to the file on the disk.

Specified by:

getCanonicalPath in interface RrdFileBackend

Returns:

Canonical file path

Throws:

IOException - Thrown in case of I/O error

getLength

public long getLength()
               throws IOException

Returns the number of RRD bytes in the underlying storage.

Specified by:

getLength in class RrdBackend

Returns:

Number of RRD bytes in the storage.

Throws:

IOException - Thrown in case of I/O error.

setLength

protected void setLength(long length)
                  throws IOException

Sets the number of bytes in the underlying RRD storage. This method is called only once, immediately after a new RRD storage gets created. Sets length of the underlying RRD file. This method is called only once, immediately after a new RRD file gets created.

Specified by:

setLength in class RrdBackend

Parameters:

length - Length of the underlying RRD storage in bytes.

Throws:

IOException - Thrown in case of I/O error.